Zhang Xuezhi, Gao Guixia, Wang Wei, Wang Jin, Wang Lina, Liu Tianxi
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai201620, China.
Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi214122, China.
ACS Appl Mater Interfaces. 2022 Oct 26. doi: 10.1021/acsami.2c14575.
The long-term operation of a Li-metal anode remains a great challenge due to the severe dendrite growth in an organic liquid electrolyte. To protect a Li-anode surface from continuous corrosion by an electrolyte, a consistent and robust solid electrolyte interface (SEI) is an essential prerequisite. This work proposes a secure gel polymer electrolyte, which is in situ constructed via a facile polymerization process of vinylidene carbonate inside Li-metal batteries. The liquid components that are not involved in polymerization are well entrapped in the poly(vinyl carbonate) framework, leading to a high oxidative stability of up to 4.5 V (vs Li/Li). A LiN-LiF-reinforced SEI resulting from the reduction of fluoroethylene carbonate and lithium nitrate additives has a synergistic effect on the suppression of Li-dendrite growth. The densely packed Li deposition behavior is revealed by in situ/ex situ microscopic observations. Steady cycling of over 2500 h with a relatively low voltage hysteresis is achieved by the Li||Li symmetric cells. A Coulombic efficiency above 96% upon long-term cycling is available for the asymmetric Li||Cu cells. The smooth operation of batteries with commercial LiFePO cathodes further indicates that the SEI with homogeneity in composition and structure prompts Li deposition with alleviative dendrites.
由于在有机液体电解质中锂枝晶严重生长，锂金属阳极的长期运行仍然是一个巨大的挑战。为了保护锂阳极表面免受电解质的持续腐蚀，一个一致且坚固的固体电解质界面（SEI）是必不可少的先决条件。这项工作提出了一种安全的凝胶聚合物电解质，它是通过碳酸亚乙烯酯在锂金属电池内部的简便聚合过程原位构建的。未参与聚合的液体成分被良好地包裹在聚碳酸乙烯酯骨架中，导致高达4.5 V（相对于Li/Li）的高氧化稳定性。由碳酸氟乙烯酯和硝酸锂添加剂还原产生的LiN-LiF增强SEI对抑制锂枝晶生长具有协同作用。通过原位/非原位显微镜观察揭示了密集堆积的锂沉积行为。Li||Li对称电池实现了超过2500小时的稳定循环，且电压滞后相对较低。非对称Li||Cu电池在长期循环时库仑效率高于96%。使用商用LiFePO阴极的电池的平稳运行进一步表明，具有均匀组成和结构的SEI促使锂沉积时枝晶生长得到缓解。
